Zigzag spring unit having closed supporting end



Jan. 4, 1955 H. c. FLINT ZIGZAG SPRING UNIT HAVING CLOSED suPPoRTIficEND 2 Sheets-Sheet 1 Filed April 22, 1949 Elli INVENTOR.

BY m Y/ZML Jan. 4, 1955 H. c. FLINT ZIGZAG SPRING UNIT HAVING CLOSEDSUPPORTING END Filed April 22, 1949 2 Sheets-Sheet 2 INVEN TOR. u h/M aUnited States Patent ZIGZAG SPRING UNIT HAVING CLOSED SUPPORTING ENDHyland C. Flint, Birmingham, Mich., assignor to American Metal ProductsCompany, Detroit, Mich., a corporation of Michigan Application April 22,1949, Serial No. 89,114

1 Claim. (Cl. 155-179) This invention relates to spring constructionsembodying a plurality of pro-arched sinuous or zigzag spring strips ofthe type disclosed and claimed in Kaden Reissue Patent No. 21,263, and,in particular, refers to such a spring per se.

In spring constructions of the type indicated it is desirable formanufacturing reasons, as well as for the sake of lightness, to have thegage of wire from which the spring strips are formed as small as iscommensurate with satisfactory spring characteristics, the latterincluding, as desiderata, uniform resiliency of the entire springsurface and also conformability to the contour of objects resting on thespring surface. Hooks law, of course, is the governing consideration inthe selection of wire gage, but its influence can be circumvented byproviding load carrying supports for sinuous strips, these being inaddition to the required connections to the frame members. Such supportshave a noticeable effect on the conformability and uniformity of theresilient spring surface and prior attempts to reduce the wire gage andspring weight by the use of additional supports have been often markedby the presence of hard spots in the spring construction which refuse tocomfortably conform to the contour of an object placed thereupon.Additional supports of this nature are also employed to regulate theunloaded contour of the resilient surface itself and it will beappreciated that use of the supports for this purpose creates thepossibility of conflict with their use to obtain the minimum size ofspring wire and the optimum spring characteristics.

It is the general object of the present invention to provide additionalsupports for sinuous spring strips which tend to reconcile conflicts ofthe type indicated and furnish beneficial effects to sinuous springconstructions from all the standpoints mentioned above, viz.,manufacturing, spring chaarcteristics, and contour.

It is a more particular object of the invention described herein toprovide a spring construction for the backs of body rest devices whichfeatures improved spring characteristics such as uniformity of resilientdeflection and conformability, improved control of contour, and reducedcost of manufacture.

These and other objects of the invention are accomplished by means ofthe present construction which employs sinuous spring elements that arepreferably an integral part of the sinuous spring strips themselves asthe additional supports for the strips, preferred embodiments of theprinciples of this construction being shown byl rwfiiy of illustrationin the accompanying drawings in w 1c Figure 1 is a perspective view of abody rest device with the back construction broken away to show theimproved sinuous spring strip;

Figure 2 is a plan view of a back frame with the present spring stripsattached thereto;

Figure 3 is a section taken on line 3-3 of Figure 2;

Figure 4 is a diagrammatic view of the spring of Figure 3, showing themanner in which the resilient surface is deflected by graduallyincreasing uniform loads applied at the points indicated by arrows;

Figure 5 is a side elevation of modified form of spring strips attachedto a frame;

Figure 6 is a side elevation of the spring of Figure 5 prior toattachment to the frame, showing the pre-arched condition thereof; and

Figures 7, 8 and 9 are side elevations of other modified forms of theinvention.

2,698,651 Patented Jan. 4, 1955 As shown in Figs. 1 and 2, springconstructions of the type herein referred to may be embodied in the seatand back cushions 1 and 3 of an automobile seat or body rest device 5.The back construction of Fig. 2 comprises a plurality of laterallyspaced sinuous spring strips 7 which may be secured to the frame 9 bymeans of the novel clips 11.

As shown best in Fig. 3, each sinuous spring strip 7 has a longitudinalportion 13 which will be referred to herein as a web, it beingrecognized that the webs of the plurality of springs 7 comprise, incombination, a resilient surface. It is this surface, and therefore theindividual webs, which is provided with the desired contour and springcharacteristics as mentioned hereinbefore, and it will be recognizedthat by forming it from wire having a minimum size consistent with therequired resiliency, that the difliculties and expense of manufacturingwill be minimized. In order to attach the webs 13 to the frame,

the strips 7 have left and right portions 15 and 17 which are bentinwardly beneath the webs 13 and which may be connected to the websthrough spacer loops 19, the latter serving to increase the overallheight of the spring con struction, but because of their substantialperpendicularity to the webs, adding little or no resiliency thereto.The left and right portions 15 and 17, which may be regarded as endsupports or attachment strips for the web, begin at the loops 19 and fordescriptive purposes are regarded as terminating in loops 21 which aresecured to the frame 9 by clips 11 as already described.

According to the invention, the additional left and right supports 22and 23 for the Webs 13, and thus the resilient surface, are inwardextensions of the attachment strips that are curved upwardly andconnected to the web 13. In Fig. 3 the supports or extensions includethe portions 24 which extend inwardly from the loops 21 and, withrespect to the attachment strips 15 and 17, are more or less symmetricalthereto. The supports further include outwardly and upwardly extendingrectilinear portions 25 that are secured to the Webs 13 by means ofsuitable clips 27.

It will now be recognized that the additional supports 22 and 23 changethe stress pattern in web 13, one such change consisting in a reductionof unit stress whereby it is possible to reduce the size of Wire fromwhich the springs 7 are formed. The resiliency, however, is notadversely affected in any way since the supports 22 and 23 arethemselves resilient and, in fact, possessed of compound resiliencybecause they include two portions 24 and 25, each of which is capable ofelastic bending between its extremities. The supports 22 and 23 alsoaffect the deflection of various sections of the web 13 under load. Fig.4 shows a typical deflection pattern for the spring 7 under theinfluence of increasing loads which were applied uniformly to the web 13at the arrows identified by the reference character P. The uniformity ofweb deflection is striking and the manner in which the supports 22 and23 deflect to bring about this result is apparent. It will be evidentthat there are no hard spots in the web 13 and that it will readilyconform to objects placed thereon. Inasmuch as the spring strips 7 arepre-arched on a smaller radius than that which they have when secured tothe frame 9, they are under stress even when no external loads areplaced thereon. The web 13 therefore occupies a position, i. e., assumesa contour, which is dependent upon the shape of the supports 22 and 23and the points at which these supports are connected to the web. Thesupports 22 and 23 can therefore be used as a simple means forcontrolling the contour of the web. This control is exercised, ofcourse, by varying the shape of the supports 22 and 23 and their pointsof connection with the webs 13.

Comparison of the embodiment 7a of Fig. 6 with that of Fig. 3illustrates the effect on contour of variations in the shape of thesupports 22 and 23. In strip 7a the left support 22a comprises a portion30 which is curved through almost before its connection 27 with the web13. The right support 23a is somewhat similar to support 23, but theportions 24a and 25a thereof form an obtuse rather than acute angle. Asa result of these changes in the supports 22 and 23, the spring 7a hasmore depth and its contour is considerably more rounded than the strip7. Nevertheless, it will be recognized by comparison of the securedspring 7a of Fig. 6 with the free pre-arched spring 7a of Fig. 5, thatthe contour is flatter than would be obtained in the absence of theadditional supports 22a and 23a. The arch in the spring strip of Figs. 5and 6 is such that in the free state the bent-under end sections abuteach other.

In the embodiment 7b of Fig. 7 the right attachment strip and additionalsupport are similar to those described in Fig. 3 and are thereforeidentified by the same reference numerals 17 and 23, respectively,though it may be noted that the spacer loop 19 is omitted in spring 7b.The left attachment strip b, however, has more depth than the strip 17so that the web 13 is spaced further from the frame 9 at its left thanat its right end. The left sup port 22b comprises an arcuate extension34 of the attachment strip 15b, but it is curved on a much larger radiusthan the extension 30 of strip 7a and is connected to the web beyond themidpoint thereof. Because of its length and slight curature theextension 34 provides a relatively soft support 22b for the web 13 ofstrip 712.

The embodiments of Figs. 8 and 9 demonstrate that the beneficialfeatures of the invention may be obtained with only one additionalsupport. In Fig. 8 the spring 70 has a right attachment strip 17 whichis a simple, arcuate, rebent extension of the web 13 as before. Thefront end support or attachment strip 150 extends downward from the webin a substantially rectilinear manner but is curved adjacent theconnecting loop 21, and a comparatively lengthy arcuate extensionthereof comprises the lower portion 240 of the left additional support220. A V-shaped supporting end portion 28 of the support 22c extendsupwardly to the Web 13 and is connected thereto by the clips 27.

In Fig. 9, the front support 15d for the strip 7d comprises aconventional outwardly opening V-shaped strip extension 40 which hasspacer loops 42 connecting it to the web 13 and at the apex of the V togive added depth. The end support 17d and right additional support 23dare likewise adapted to give added depth to the strip while supportingthe web 13 with the characteristics of a rather flatly curved continuousspring element. Thus, the additional support 23d is connected to anintermediate point of the web by spacer loops 50 while the end support17d is connected to the web by spacer loop 52. Extending outwardly fromthe loops 50, the additional support 23d has an arcuate section 54 whilethe end support 17d has a similar arcuate section 56 extending inwardlyfrom the loop 52. If fully extended, the sections 54 and 56 would meet,to form a continuous arcuate support for the spring. However, sincedepth is required, spacer loops 58 and 60 extend downwardly from thesections 54 and 56, respectively. The loops 58 and are interconnected byan arcuate section 62 which, it will be recognized, is merely aconnection between sections 54 and 56 displaced downwardly. Inasmuch asthe spacer loops 50 and 52 are substantially normal to the web 13 andthe spacer loops 58 and 60 are substantially normal to the sections 54and 56, they provide substantially no resiliency to the supports 23d and170,. Thus, the spring characteristics of these supports are those of acontinuous element composed of sections 54, 62, and 56, but the supportshave been endowed with the required depth by means of the spacer loops.

From the preceding embodiments it will be seen that the invention may beembodied in many forms, hence, it is not intended to be restricted tothe particular shapes shown. It will also be recognized that theconnections of the additional supports 22 and 23 to the web 13 may bearranged therealong to provide the desired contour and springproperties. Further effects can be obtained also by shifting the pointsat which the strips are connected to the frame 9 by means of the loops21 and clips 11.

What is claimed is:

A single spring unit embodying a strip made of wire bent back and forthto provide lateral portions joined by end portions which space thelateral portions, said strip having a central arched web section forsupporting a load, intermediate straight sections abruptly bent from theends of the web section to extend laterally thereof, and end sectionsabruptly bent from the intermediate sections to extend laterally thereofbeneath said web section, both of said end sections being archedreversely from the Web section with the ends extended upwardly intoengagement with the web section, at least one of said extended endsbeing straight.

References Cited in the file of this patent UNiTED STATES PATENTS Re.21,263 Kaden Nov. 14, 1939 2,371,407 Neely Mar. 13, 1945 2,386,456Haberstump et al. Oct. 9, 1945 2,440,001 Blumenstadt Apr. 20, 19482,526,183 William et al. Oct. 17, 1950 FOREIGN PATENTS 667,407 FranceJune 17, 1929 498,160 Germany Nov. 12, 1931 683,718 Germany Nov. 13,1939

